I recall hearing that Rav Moshe Feinstein rules that one should donate a tenth of his time to learn with other Jews, in addition to the more commonly accepted 'tithe' of money. The only source I was able to find this referenced in was an Aish article that quotes an interview of Rav Moshe in the Jewish Observer where he made that claim.

Does anyone know if this is brought down anywhere else, specifically in Igros Moshe? Or alternatively, what it would be filed under in the Yad Moshe, as I couldn't find it?

Thanks!